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Physical Geography > Tectonics (nobody cares) > Flashcards

Tectonics (nobody cares) Flashcards

1
Q

What are the 3 main types of plate boundary?

A

Convergent, divergent, transform.

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2
Q

What is the Benioff zone?

A

Area where friction is created between tectonic plates, resulting in intermediate and deep earthquakes.

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3
Q

Give the seismic and volcanic activity of destructive (convergent) ocean and continent plate boundaries.

A

High magnitude (7-9).
Explosive eruptions (5-6 VEI scale).

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4
Q

What landforms do destructive (convergent) ocean and continent plate boundaries form.

A

Ocean trench and fold mountains with volcanic peaks.

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5
Q

Give the seismic and volcanic activity of destructive (convergent) ocean and ocean plate boundaries.

A

Moderate to high magnitude (7-9).
Explosive (5-6 VEI scale).

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6
Q

What landforms do destructive (convergent) ocean and ocean plate boundaries form.

A

Island arcs and ocean trenches.

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7
Q

Give the seismic and volcanic activity of convergent (collision) continent and continent plate boundaries.

A

Moderate magnitude (6-8).
Usually no volcanic activity.

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8
Q

What landforms do convergent (collision) continent and continent plate boundaries form?

A

Fold mountains.

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9
Q

Give the volcanic and seismic activity of divergent (constructive) plate boundaries.

A

Low magnitude (5-6).
Effusive eruptions (1-3 VEI).

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10
Q

What landforms do divergent (constructive) plate boundaries form?

A

Ocean ridge with central rift valley. Faulting at right angles. Volcanic islands.

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11
Q

Give the volcanic and seismic activity of conservative (transform) plate boundaries.

A

Moderate magnitude (6-8).
Very little volcanic activity.

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12
Q

What landforms do conservative (transform) plate boundaries form?

A

Ridges and scars on surface.

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13
Q

What is the difference between the epicentre and the focus?

A

Epicentre - most intense area of the earthquake on land.
Focus - the area underground where the most pressure is released during an earthquake.

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14
Q

Describe how paleomagnetism provides evidence for tectonic plate movement.

A

Opposite directions of magnetic field patterns found on ocean floor. Due to changing direction of global magnetic fields every 100,000 years. Proves new rock is being formed at divergent plate boundaries.

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15
Q

Describe how irregular rock type and fossil patterns provide evidence for tectonic plate movements.

A

Matching fossil and rock types in different continents. Cynognathus reptile fossil found in South America and Africa. This evidence, paired with fitting continental shelf shapes allows for a theoretical construction of old plates - Pangea.

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16
Q

What are intra-plate earthquakes and volcanoes caused by?

A

Hot spots from mantle plumes
Potentially exploiting weakness in rock structure (maybe from previous tectonic activity).

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17
Q

How fast are primary waves and what do they travel through?

A

Fastest
Solid and liquid

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18
Q

How destructive are primary waves (move back and forth?

A

Only damaging in most powerful earthquakes.

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19
Q

How fast are secondary waves and what do they travel through?

A

60% speed of p waves
Solids only

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20
Q

How destructive are s waves (side to side movement)?

A

Very damaging.

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21
Q

How fast are love waves and what do they travel through?

A

Slowest
Surface of crust

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22
Q

How destructive are L waves (side to side)?

A

Most destructive.

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23
Q

What is liquefaction?

A

Secondary effect of an earthquake where the shaking causes surface rocks and soils to lose strength/support and become more liquid than solid. Buildings and roads tilt/sink.

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24
Q

What was the magnitude of the earthquake in Christchurch 2011?

A

6.3M

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25
Q

Why was liquefaction so bad in Christchurch 2011?

A

Soil and rock type lead to exaggerated liquefaction. Contrasting resonance in soil layers caused soft layer 30m thick to rise up and slap back down. Strongest ground motion on record.

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26
Q

What % of CBD buildings were damaged in Christchurch 2011?

A

80%

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27
Q

What was the death toll of the Christchurch 2011 earthquake?

A

185

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28
Q

What was the total cost of the Christchurch 2011 earthquake?

A

$28bn

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29
Q

How much international aid was provided to Christchurch 2011?

A

$6-7 million.

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30
Q

What was done in Christchurch after 2011 to prevent damage again?

A

Grids of stone columns inserted into soil under buildings 10m deep with grid of sand and gravel. Stabilises ground, redistributes weight, less stress on ground. Example of aseismic technology.

31
Q

What are most tsunamis caused by?

A

Water column displacement due to undersea landslides, earthquakes, eruptions.

32
Q

Explain how water depth near the coast impacts tsunami height.

A

Deep - may be barely noticeable due to long wavelengths.
Shallow - friction at base slows tsunami down, shortens wavelength and increases height up to 20x.

33
Q

Why are composite cone volcanoes more explosive than shield volcanoes?

A

Composite cone volcanoes formed by more viscous lava (thick). Traps more gas, build up of pressure is more. When pressure suddenly released during eruption, the pressure causes them to be more explosive.

34
Q

What area jokulhlaups and explain briefly how the form.

A

Flood of meltwater from a volcano erupting beneath an ice cap or glacier. Meltwater forms underground lake, melts more ice. Causes ice to lift above bedrock, releasing all water and debris to wash away everything in lowland areas.

35
Q

Where have jokulhlaups been formed before and what was the impact?

A

Iceland 2010 EFJ eruption. They were anticipated so roads were shut and channels for water built, limiting damage.

36
Q

Name the types of lava from most to least viscous.

A

Rhyolitic, andesitic, basaltic.

37
Q

What is tephra?

A

Solid molten rock fragments ejected into the air due to explosive eruptions. Can be more solid or fine (ash). Atmospheric ash can travel thousands of miles.

38
Q

What are pyroclastic flows?

A

Dense mixture of super heated tephra and poisonous gases flowing down a composite cone volcano.

39
Q

What are lahars?

A

Water mixed with volcanic deposits flowing down already-existing valleys. May be caused by snowmelt/icemelt due to temp increase. Dangerous due to fast velocity and capacity to hold large amounts of material.

40
Q

What is a hazard?

A

An event that disrupts normal daily routines of the population.

41
Q

What is a disaster?

A

When a hazard exceeds a threshold of damage, economically or socially.

42
Q

How does the UN define a mega-disaster?

A

2000 deaths, 200,000 homeless or GDP reduced by 5% or reliance on international aid for over a year.

43
Q

Why are volcanoes considered less hazardous than other tectonic hazards?

A

Greater temporal and spatial predictability. Smaller effected area.

44
Q

Why is the MMS scale used more than the richter scale in the scientific community?

A

MMS more accurate/reliable as it considered more factors.

45
Q

How many commercial flights were cancelled due to the EFJ ash cloud in 2010?

A

100,000

46
Q

What was the estimated total cost of the EFJ eruption in Europe?

A

$5bn

47
Q

What was a example of a global impact of the EFJ eruption 2010?

A

Kenyan exports of flowers via airline cancelled - loss of $1.3m per day.

48
Q

Why is the PAR model important?

A

It identifies all factors that humans can influence to reduce the risk and impacts of hazards. Makes it clear to governments and aid organisations were money should be invested to prevent disasters.

49
Q

What is the risk equation?

A

risk = hazard x vulnerability

50
Q

Name measures that meant Japan was prepared for a tsunami before the Fukushima disaster 2011.

A

Low corruption meant that strict building regulations to build aseismic buildings were enforced.
Emergency system gave some people a minutes warning.
Many offices and homes equipped with emergency kits.
Vulnerable areas already had 10m defence walls.

51
Q

Why was the 2011 Tsunami in Japan a disaster?

A

Fukushima nuclear reactor not prepared for tsunami. 20,000 death toll.

52
Q

What was the economic cost of the Fukushima disaster?

A

$7bn per year.

53
Q

What was the immediate response to the 2011 Japan disaster?

A

Over 100,000 defence troops mobilised within 24 hours.
Bank of Japan gave vast amounts of money to private banks to protect economy.
Immediately accepted foreign aid.

54
Q

What was the global impact of the 2011 Fukushima disaster?

A

Increased awareness of the risks of nuclear power.
Germany massive phasing out of nuclear power (WW2 hangover).

55
Q

What was the magnitude of the Haiti 2010 earthquake?

A

7.0M

56
Q

Haiti earthquake death toll.

A

230,000

57
Q

Haiti earthquake economic cost.

A

$8bn

58
Q

What were the secondary impacts of the Haiti earthquake?

A

Outbreaks of cholera
Crime
Temporary shelters
2 million without water or food

59
Q

Why was international aid delayed in response to the Haiti earthquake?

A

Only airport and port were impacted by earthquake.
Poor organisation.

60
Q

Which country has the highest World Risk Index in the world?

A

Vanuatu.

61
Q

Why is Vanuatu at such a risk to disasters (physical factors)?

A

Multiple hazard zone: risk of volcanoes, earthquakes, cyclones, sea level rise.
Area of tectonic complexity
Pacific ring of fire of volcanoes

62
Q

Why is Vanuatu at such risk to disasters (human factors)?

A

Isolated islands - no mobile phone connection
Low HDI
Small islands - little space to move to avoid disasters
Low coping capacity - reliant on foreign aid

63
Q

What disasters has Vanuatu experienced recently?

A

Cyclone in 2015
Frequent strong earthquakes e.g. 7 magnitude 2015
Frequent volcanic eruptions

64
Q

Why may people choose to live in tectonically risky areas?

A

Affordable housing in more dangerous housing.
Economic opportunities - fertile farmland.

65
Q

Give 3 reasons why disasters appear to be more frequent recently.

A

Urbanisation - increased flood risk.
Climate change - increased tropical cyclone frequency.
Increased monitoring, reporting and communication.

66
Q

Mt. Pinatubo Philippines 1991 eruption death toll.

A

800

67
Q

What caused destruction of towns and villages in the Philippines 1991?

A

Pyroclastic flows destroying towns and villages.

68
Q

What was the global impact of the 1991 Pinatubo eruption?

A

SO2 released caused global cooling as part of ash cloud.

69
Q

What was the death toll of the 2004 Indian ocean Tsunami?

A

230,000

70
Q

What were the local long term impacts of the 2004 tsunami?

A

Tourism and fishing industries.

71
Q

What was the global impact of the 2004 tsunamis?

A

Billions in aid - massive global charitable effort.
Highlighted the importance of disaster management.
Raised awareness of climate change risks.

72
Q

What is the most effective phase of the hazard management cycle?

A

Modifying vulnerability rather than modifying event or loss.

73
Q

What can be done to moderate vulnerability to tectonic hazards?

A

Land use zoning.

74
Q

Describe the San Fransisco case study for land use zoning.

A

Earthquake vulnerable. Strict anti-seismic building regulations. Development in particularly vulnerable areas is very limited.

Physical Geography (5 decks)

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